Distillation of tar to produce heavy creosote oil



NOV. 16, 1943. ZAVERTNlK 2,334,667

DISTILLATION OF TAR TO PRODUCE HEAVY CREOSOTE OIL Filed Aug. 29, 1940 6' (bimemrer 4;:02160 INVENTOR I fife/7i Zarerzm'f BY i re 6 Z ATTORNEY Patented Nov. 1943 j .Corporation; a, corporation'of-New York "This invention relatesto .irrlbrovedfniethdd of distilling tar to produce valuable creds pe ecmpositions. By tarf is 'meantncoal'tarincliiding coke oven tar, gas house tarfland coal tarsjobe tained from thelowjtemperature carbonization or gesificationbf coal and water? gastar'. 1

'Tars such as coke oven tan'gas house tar, or water gas tar, contain constituentsWhichfaxie readily; decomposed or polymerized at the highi 10f temperatures j encountered in t tar distil1a'tion;

1 sible t Such decomposition of polyrnerizationin o'rdi; V

nary tar distillation processes gives an'unsatisa,

factory yield of distillate oilan'd 'anroil product having a'high coke residue (as determined by American Society for Testing MaterialsTest DV 168-27). In United States Patent No. l,75 .,8 16,

granted Mayfw, 1930, directed to ajoint invention of A'. A. .l 1IacCubbin and myselfTisjclisclosedl a process of distilling tar t'o giveiincrease d yields,

of distillate 'oils andhigh melting point pitches; This process involves flowing "the tar through a coil still to heat the tar withcutvaporizationiv'and introducing theheatedQtar into a flash vb o'x where.

a portion of the tar vaporizes,' leaving a pitch residue whichis subjected to'a vacuumi urea ment for distillation of furtheroils; The vapors released in'the flash box are passed to all tional condenser and are progressivelycoole to i acticnshlg has Evans thatfth time a t r:

condense the vapors into the desired fractions',

such as creosote oils, naphthalene and tar acid;

oilsf' Many millions'of gallons of tarihave'beeri distilled commercially in acccrdancefwith the invention of this patent, Inthis distillationfif tar, the vapors released in' the fiashboxat ele vated temperatures are cooled s1owly,"inv0lving a considerable period of cooling time, substan tially in excess of two minutes. 1 While valuable creosoting oils meeting commercial specifications have heenproduced bythe1-method-ofthis patent; l v.

ithas beenfcund that thismethod attirnesre:

suits in the production of'heavycreosote oil 7 containing a relatively high coke residueu flBy the expression heavy creosote soil is meant an oil of about about 'boils above 3003 .C. 15130 pro duce heavy creosote oils meeting specifications V requiring 10w coke residue contents, it has been necessary to redistill the .oil, with consequent lossof reclistillationoperation. I t V r It is an object of this invention to distill, ax; in a simnle and expeditious manner to produce a high 1e and low free-carbon content. 7 Otl'ifiif 9 je'cts and adva-ntages of this jinventionfwill ap; 1

near hereinafter. H l e In accordance with this invention a coni ed land expertise andlab'o'r involved in'Qthe yield oi heavy creosote oil having allow coke stream efftar is heated rapidly and underi prefsisure to a temperature above 5705 11; preferably I to a temperature ofahout 780i to 8QO ,,F.,fwhi1e avoiding-released vapor; and'the heated tar'is mattress V distillate ns}.

i ne on t f n? m n? volatile, per ain theme E T s1 re e ed vapors, leaving theyexpansionzonea a.

ij niiifl t sex i ns vapors passing through t densa te is" withdrawn from each "path tjfs 'ep'allat to ovej the; eondensedhea-vy creosote, oil i io m cn actiwitnrhe hofifre idu i vapors substantially V j as rapidly, as.formed,thereby materially reducing, l the time during; Whichthe heavygcreosotcci suhjected to temperatures above 5170. ;v iHow ever,ithe condensing vzone may. ccr'nprisea series; 7 1 of relatively long vhcrizorita-l'.cooling.paths each path havi'n' twp, or Q more 1 condensate outlets so separationinto f ulft .iL'e Qth'e timedu'rin'g which each particlelot heavy r o cte s. subjected to tem e tu ove 79i. shs ld neid -mi uie s n rre t eral ly' should bejless'than ten seconds." Qperaf tion' inaccordanc'e with these'conditions, I hav v found gives a high yield oi heavy creosoteoil 1 7 7 having alovv"fcokefresidue f c I hay'e also found that the coke residueandl free carbonicontent of the heavyfcreos'ote oil may;

be furthervr'educed by condens in g agportionlof the vapors frorfnth'e flash box, and returning that; condensate .to the flash; box.

The invent n des Fi ure, isjei d mm tl ll w ns 'or"-an,ar--' inven s reens s es re ib thivrac mventio' beidistil pu'xnped'frcmeither orboth of tanks; .l 'andZ rude'tar' c'ontaliningupto 6 per cent" ath'ofthecondensate]withinthe hqtflsh D h i dns u it'@dlinicontact af v k Qt fv'apors "isfrelativelyjsliort; "The s y el var' ors."atn aii' emne ature below 570 F.

is i a i onden erl r' ra ei heflcondensateg '1 rezncyedgfrpin .the vapcrs takes with itjthe fftar; I fogj which would norniallybev Qariiied along an condense with ,the g a qrfsg and thereby. reduces the coke residue alldfl'fie ca on'contentoffthe' fietibn with th acc ih nrin fir w iii v ili ,7

eu cf S v1 appeals btl airvinsq t. ess of, inyinvention comprising' storage tanks;

lanez fort he jtar. to he distilled; a. continu v I and a. condenser'assernblyf condensation of heavy creosote oil. fI far to.

V erably the tar contains from 2 to .3 per. cent or.

moisture. The tar, usually a mixture. is forced through pipe 1 by pumps 8 and 9 to heat exchangers 3i! and thence through-a pipe to the con denser units i I of the condenserassemblyj and to condenser unit 5, where-itlpasses' inindlrect heat exchange relation with the vapors in the respective condenser units serves'a a "cooling. medium, and receives a preliminary heatingf.

II and in an order whichisthe reverse oi the order in which the vapors to be condensed pass through the units5 and H. Fromathe-condenser units H and 5, the tar flowsv to the pipe ccilstill} through supply pipe 1 2. Alternatively, crude tar'may be pumped from one tanl through V pipe 'l into" heat exchangers 39; thence through. a pipe into condenser units "ii, and dehydrated.

or crude tar'ma'y be pumped from another'tank through pipe *28 whi'ch; meetssupply pipe i2.

Tar flowi'rrg. f'ror'n condenserunit '5 through pipe '2' thus mixes with. tar from pipe 28 before en-' teringthe' pipe coirstfill 3. The quantity of tar pumped through the condensers? Hand 5 depends upon the degreeof fractionation desired; the. smallerthe :quantity of' tar pumped, the

sharper (narrower) the oil fractionation ob-.

tained. IThe'tar; usually. mixed, passesithr'ough tl'iepipe coilstiilj" rapidly and under pressure and: isiheated in the pipe' coil still toa; temperature above 570? F1, preferably from .780? to 800511, and passed through pipciilto the flash box I, constituting an expansion zone; which is ata ressure lower than thatin the still 3, and preferabiyat atmnspheric pressure or approximately' so. The rate of flow. of the tax: per square inch oi injtern'al transverse area of pipe exposed.

to heat is preferably equal to 0.5 to 1.5 cubic feet per minute; in other words the tar flows in cubicv feet perrninute at a rate equal to aboutv 10 to 14 per. cent o1.the' cubical capacity in cubic feet of the pipe coil. still. In the flash box 4 the oil content ofthe" tar vaporizes, leaving pitch; and the pitch is withdrawn from the flashbox, de-

sirably to a vacuum box (not shown), where ad-', ditional 0118.316 distilled off leaving behind. a

melting point pitch.

The oil vapors from the flash box 4 may nextbe passed rapidly through condenser unit 5 .for "tar fogf," removal. 'Where the tar was heated initially to a temperature or from 780 to 800"" the temperature of the vapors is preferably reduced in the 'unit5 to between 730 to 760.

andgajportion of the. oilvapors, which maybe from, l to 3' per cent. preferably about 1.5 per cent based on ta-r distilled is condensed. "This condensate flows. back to the flash box 4 by gravity, carrying with it the tar fog. removed from the vapors. The lower boiling. portion of thecondensate is 'revapori'zed in the flash box 4 and passes again to thelcondensers.

I: Thefvapors fromthe .tar..fog.? removal condenser 5, or from the flash-box l in case the unit. 5

isnotemployecl. arelthen flowed rapidly through. the condenser units" ffof condenser ass'e'mbly 6..

Eachjunit ii provides a relatively s'hort-horia through: the" condenser units .The tar is flowed through the condenserunits' I provided each unit has an individual outlet so that the condensate does not flow through several units, 'The 'vapors are flowed at such rate through these condenser units that each particle 5 of the vapors passes from the flash box through 11the tar removal condenser 5 and the condenser assembly 6 in less than two minutes, and prefer- .ably less than ten seconds. The cooling capacity "of the condenser units I l is regulated in conldtrolling the' flow'of tar or other cooling medium ll so that the vapors from the flash box are cooled from an initial temperature of about 760 to 790 F. to a temperature below 5'70 F., say within the range 15 of 530 to 560 F., and preferably to a temperature of about 550? F., and the heavy creosote oil is condensed in passing through the units H. The heavy creosote oil condensate flows counter tothefflow of vapors in each condenser unit and i'sflwithdrawn separately from each unit ll so that the heavy creosote oil is removedfrom contact with'the hot vapors and hot condenser shells in the condenser-units I I substantially immediately'after formation. The heavy creosote oil condensate from' the separate units H flows through the threeway valves to the condensate line i5. By manipulation of the valves M the condensate may be divided into, three parts and flowedfthroughthe lines 16, to the condensate receivers H, or all of the condensate may be passed to any desired receiver i1.

I'havefoundthatlthe heavy creosote oil condensed in the condenser units ll of the condenser assembly 6' under the conditions of oper'ation outlined above contains less than 1.5 percent coke residue, usually less than 1.0 per cent,.as compared with as much as about 4.5 per cent obtained by'methods heretofore in use. Uncondensed vapors of lower boiling oils are 40 withdrawn from the condenser assembly at i8 5'4 and may be subjected to any desired fractional v condensationto obtain fractions such as light creosote oil,'naphthalene, tar acid oil and light solvents. f In the practice of my invention I have found itdesirable to employa single condenser unit of the type shown in Figure 2' asthe tar fog removat condenser unit 5, and a number of similar units arranged in series, with the vapor outlet of one unit connected to the vapor inlet of the succeeding'unit, as the condenser units i i of condenser assembly 6 for condensation of heavy creosote oil. Briefly. each condenser unit comprises a 'horizontally disposed substantial cylindri'cal shell I! having a vapor inlet 20 and vapor outlet 2| located near opposite ends of the shell f9 to provide a path for the vapors through the shell} Hli past two hairpin'tubes 22 within the shell I8 which'c'onstitute the cooling surface of the condensing, unit. These tubes 22 extend within theshell [9 parallel to the axis of the shell and are supplied with a cooling fluid, which is preferably the .tar to be distilled, from the header 23. The header isprovided with a tar inlet 2 and a tar outlet, 25 and is so constructed that the tar flows successively through the two hairpin tubes 22 of each condenser'and then through outlet '25 torthe next condenser of the series countercurrent' to the flow of vapors through thecondensers- Depending on the length of the condenser unit, one ,or. more liquid outlets 26 are disposed-at the bottom of each shell i9 so that condensateformed ineach shell flows along a relatively' short path, preferably countercurrently v and tar fog remover condenser 5.

to the vapors, and is continuously dischargedifrom the' condenser substantially immediately after.

it is formed; The relatively large cooling surface and the 'relativelyshort condensate path to the. individual outlets 26 of the shells renderthis type of unit particularly suitablefor usein the presentprocess. i t

: Thefollowing exampleisillustrative'ofla preferred embodiment of the invention; i

Example.--Crude' tar (moisture content 3.6%)'

at a temperature of 170 F. is pumped by pump 3 through the pipe I to the condenser assembly i3 pera'ture 01' the tar is raised in passing through thelheat exchangers 30 from 170 to 400?, F. and in passing through the condensers 6 and Ejfrom 400 'to 'l0 F., and the'preheated tar is passed through supply pipe to the pipe'still3. The preheatedcrude tar flowing through pipe [2 is mixed with dry tar pumped directly through pipe 28:-into pipe l2 prior to'entering the still3. 'Ihe mixture" comprises '57 parts of l preheated crude tar and 43 parts of dry tar. The tar mixture flo'ws-throughthe coils -of- 'thestill 3"at 'arate per minute equal to 12% of the cubical capacity of the still and is there heated toa temperature of 800 F. without substantial evolution of vap'ors. Theheated tar is then discharged from the'still The temt (cube in-water method) and briquetting pitch of 170 180? F. melting point (cube-in-air method),

may be produced'by this; process by heating the} tar in the pipe coil still to temperatures of about 640 to 660 F. and about 700 to 720 F.',res'pec'- i 'tively, and cooling the vapors to a temperature below 570 F., in less than two minutes to fcon- I dense the heavy creosote oil.

' C'astiron is the'preferred metal fromwhich the condenser is fabric'at'edforuse in the con- V densation of coal tar. Fordistillation '01 other 7 materialsother suitable metals resistant to corresion'may be used- It will be understood the condenser'system is suitably insulated tdprevent e V excessive cooling to obtain the desired degree of condensation and loss of heat tothe atmosphere;

Since certain changes may be made without departing from the scope of the invention,"'e .'g.

the invention maybe carried out in equipment r 7 other than'that illustrated, it is'intended that the 7 above shall be interpreted inan illustrative and 3' through pipe l3 to the flash box 4, where the on f content of the tar is flashed into vapor, leaving behinda pitch having a melting point of 245 F; (cube-in-airmethod); which is withdrawn and subjected to'vacuum' treatment' The vaporsto gether with entrained tar f fog, are passed throughthe condenser unit 5 whereinthe tern-t per'ature is reduced to 50F. and 1 5- per cent of the vapors based on tar distilledare condensed to remove tar fog and the condensate is returned to the flash box :arrying' theremoved tar'with it. f The vapors from the condenser 5 areithen passed through the condenser assembly 6 wherein e not in at-limiting"sense.

prises'flowing' tarjin aconflnedstrear'n, heating the stream f tarto' 'a temperature above 570. 7

F. but below 800 F. without substantial vaporization of the'tar introducing heatedtartfrom'the stream into an expansion zone to vaporize a po tion ofithe oil content of the tar flowing the vapors thus produced through atcooling' zone "to condense a portion of the vapors, passing the.-

condensate thus for med'" to said expansion zone in' contact'with the vapors leaving said expansion the temperature is reduced "to 5 60 F.ffor con- Q densation' of the heavy creosote foil fraction. The

time factor for the passage of vapor through the condenser unit 5 and condenser assembly 6 is about seconds. The heavy creosote oil job-1 tained" from the unitsof the condensertassembly 6 has a boilingralnge lot from 220 ,tO'abOVeAOO? C., lessthan 10% of which boils below 3003 C. and atleast 80% of which boils downbelow400f C., and contains only LG per cent coke residue.

Thus it"will be seen theinvention'jprovides a novel process for effecting the distillatiomofjtar in a simplejefiicient and ,iexpeditious manner to obtain good yields of highqualityheavy creosote oil without re'distilling the oil By: condensing the heavy'creosote oil from thetar distillate vapors whilepassing the vapors through the condensers, removing the creosote oil condensate from contact with the hot vapors and .hot shells zone, thereby retumlng'to said expansion zone the condensate formed in 'theTsaid' cooling zone and the ftar fog"rem oved from; the said vapors by thecondensation of said vapors taking place in said cooling zone and thewashing of thevapors to a temperatureabove about5'l0? F. does not ar ceedtivo minutes andcontinuously withdrawing thejheavy creosote oil thus condensed, from contact withthe vapors substantially immediately 7 upon formation.

of the condensers substantially. as soon" as V v formed, and cooling the vaporsfpassin'g through the condensing zone'to a temperature below 570?. F; in less than two minutes, the content of those constituents of therheavy creosote 'oil vapors which constituents upon heating tend to poly;

merize and decompose, is gi'eatlyreduced with consequent reduction of thecoke residug. of the" oil. Furthermore; the remcval offtariog"? from the vapors prior to condensation of therheavy.

creosote oil promotes the obtentionofaproduct of low coke residue and low' free carbon content Whereas the process has been described in below'800" Ffwithout' substantial vaporizationfoi t ,the tar, introducing heated tar'ffromthe stream to an expansionszone to vaporize'porticnsofthe" e cil content; of teeter, flowing the vapors thus t 7 produced throughacoolin zone to condense p ortion 'oi 'the' vapors; passing the condensat'e r thusiormedQto saidgexpansion zonein contact withthe vapors leavinggss'ai'd fexpansionwone;

thereby returning to said expansion zonethe con densate ioi medtin the said cooling zone and the tarfog! removed from the'said'vaporsjby the;

condensation of'said vapors taking place' in said 7 connection withthe production of highmeltiii A I or i N cooling zone and the washing ofthe vapors with;

point pitch; the same process may be utilized to I 2, A l rocesscf distilling "comprises V flowing tar in a confined stream; 'heatingfthe V stream offtar to a temperature above 5,70f 'F' but t r 1 yield lowtmelting point pitch. Thus; for ex, ample, roofing pitch of 1409-F. melting point 7 I I distilling tar to produce 'a'heavy' creosote oil having a low coke residue whichlcorn said condensate taking place as thesaid' vapors and the said condensate flow respectively in contact with each' other from and'to the said expansion zone,,reva'porizing the lower boiling portion of the condensate thus returned .to the expansion'zoneand causing the vapors thus formed to fiowiwith the first mentioned vapors through thecooling zone, and passing, the vapors from the cooling zone through a condensing zone.

3. The process of =distilling tar to produce 'a heavy creosote oil having a-1ow coke residue-which comprises flowingtar in a confined stream, heating the stream of tar to a temperature of 64.0 to 660 F; without substantial vaporization of: the tar, introducing heated tar from the stream into an expansion zone to vaporize a portion of the oil content ofthe tar, flowing the vapors thus produced through-a cooling-zone to condense a portion of the vapors, passing the condensate thus formed to-said expansion zone in contact with the vapors leaving said expansion zone, thereby r e turning to said expansion zone the condensate formed in the said cooling zon and the tar fog. v

removed from the said vapors by the condensation of said vapors taking place in said cooling zone and the washing of the vapors with said condensate taking place as the said vapors and the said condensate flow-respectively in contact with each other from and to the said expansionzone,

revaporizing the lower boiling portion of the condensate thus returned to the expansion zone and causingthe' vapors thus formed to flow with the first mentioned vapors through the cooling zone,

' comprises flowing tar in a confined stream, heating the stream of tar to a'temperature of I" to 7205B, without o substantial vaporization .of the tar, introducing heated tar from the stream into an expansion zone to vaporize a portionrof the oil content of the tar,'flowing thevvapors thus produced through, a cooling zone to'condense a portion of the vapors,v passing the condensate thus formedto said expansion zone in contact with the vaporsleaving saidexpansion zone, thereby returning to said expansion zone the condensate formed in thesaid cooling zone andthe tar fog? removed from the said vapors by the condensation ofsaid vapors taking place insaid cooling'zone and the washing of the vapors with said condensate taking place as the said vapors andthe said condensate flow respectively in contact with eachother from and to the said'expansion zone, revaporizing the lower boiling portion of the con-- densate thus. returned to the expansion zoneand V causing the vaporsthus formed to flow with the 5'. 'A' process of distilling tar to produce a heavy creosote oilhaving a low'coke residue which comprises flowing tar in aconfined stream, heating the stream of tar to a temperature above 570 F. but below 800 F. without substantial'vaporizm 'tion of the tar, introducing heated tar from the stream into an expansion zone to vaporize a portion of the .oil content of the tar, fiowing'the vapors thus produced through a cooling zone to condense a portion of the vapors, passing the condensate thus formed to said-expansion zone in contact with the vapors leaving saidexpansion zone, thereby returning to said expansion zone the condensate formed in the said cooling zone and the tar fog removed from the said vapors by the condensation of said vapors taking place in said cooling zone and the washing of the vapors with said condensate taking place as the said Vapors and the said condensate flow respectively in contact with each other from and to the said expansion-zone, revaporizing the lower boiling portion, of the condensate thus returned to the expansion zone and causing thevapors thus formed to flow with the first mentioned vapors through the cooling zone, rapidly passing the va ors from the cooling zone through a series of paths to condense heavy creosote oil vapors so thatthe time during which each particle of the heavy creosote oil vapors is subjected to temperatures above about 570 F. does not exceed two minutes, and continuouslywithdrawing condensate from each path separately to remove the condensed heavy creosote oil from contact with the vapors substam tially immediately upon-formation. e 7 1 6. A process of distilling coal tar to produce a heavy creosote oil having a low coke residue which comprises flowing coal tar through a coil still to heat the tax to a temperatureof about 780 to 800971 introducing the heated tar into avapor box .to vaporize a portion of .the oil content of the tar, flowing the vapors thus'produced through a. cooling zone to condensea portion of the vapors,

passing the condensate thus formed to said vapor box in contact with the vapors leaving said vapor box,thereby returning to said vapor box the condensate formed in the said cooling zone and the tar fogvrremoved from the said vapors by the condensation of said vapors taking place in said cooling zone and the washing of the vapors with 7 said condensate taking'place as'the said vapors and the said condensate flow respectively in' contact with each other from and to the said vapor box, revaporizing the lower boiling portion of the condensate thus returned to the vapor box and causing the vapors thus formed'to flowwith the first mentioned vapors through the cooling zone,

first mentioned vapors through the coolin'gzone rapidlypassing the vapors from the cooling zone through a condensing zone to condense heavy rapidly passing the vapors irom the cooling zone through a condensing zone to condense heavy creosote oil vapors, regulating therate of flow and therate of cooling of the vapors in the condensing zone so that the time during which each particle. of the heavy creosote oil vapors is subjected to a temperature above about 570 F. does not exceed two minutes, and continuously withdrawing the heavy creosote oil thus condensed from contact with the vapors substantially immediately upon formation.

'7. A process of distilling coal tar which comprises flowing coal tar in a confined stream, heat ing the stream to a temperature of about 780 to 800 F. without substantial vaporization of the .tar, introducing heated tar from the stream to an expansion zone to vaporize portions of the oil content of the tar, fiowing'thevapors from said zone to a cooling zone, removing tar fog from the vapors by cooling them to about 730 to 760 F.

to condense from 1 to 3% of the vapors based on tar distilled during flow through the coolingzone, and passing the condensate formed to the expansion zone in contact with the vapors" leaving said zone, thereby returning to said expansion zone the condensate formed by cooling the vapors to about 730 to 760 F. and the tarfog removed from the vapors by the condensation of said vapors and the washing of the vapors with said condensate taking place as the said vapors and the said condensate flow respectively in contact with each other from and to thesaid expansion zone, and revapori'z'ing the lower boiling portionof the said condensate thus'returned to flow'and the rate of cooling of the vapors in the v paths of the condensing zone so that the time heavy creosote oilvapors regulatingthe rate of during which'each particle of the heavy creosote the expansion zoneand causing the vapors thus formed to flow with the first mentioned through the cooling zone,

vapors 8. A process of distillingcoal tar to produce a heavy creosote oil having a-low coke residue which comprises flowing coal tar through a coil still to heatthetar to a "temperature of between about 780 and about 800 F., introducing the heated tar into a vapor box to vaporize a portion of theoil content of the tar, flowing the vapors, thus produced through a cooling zone to condense a p01} tion of the vapors, passing the condensate thus formed mean vapor boXQin contact with the vapors leaving said vapor box, thereby returning to said vapor box the condensate formed in the said cooling zone and the tar fog removed from the said vapors by the condensation of said vapors taking place in said cooling zone and the washing of the vapors with said condensate'taking place as the said vapors and the said condensate flow respectively in contact with eachother from and the vapor box and causing the vapors thus'formed to flow with thefirst mentioned vapors through the cooling zone rapidly passing the vapors from .the cooling zone through a condensing zone-to condense heavy creosote oil vapors, regulating the 570 F; does not exceedten'seconds, andconoil vapors remains above a temperature of about 570- F; does not exceed tenv seconds-"and con- I tinuously withdrawing condensate from each path separately to remove the condensed heavy creosote oil from contact with thevapors' ubstantially immediatelyupon formation. c 7 10. A process of distilling ltar to produce a heavy creosote oil having a low coke residue which comprises flowing tar in a confined stream; heating-the streamfof tar to a temperature above 570 F. but below 800 F. without substantial vaporization of the tar introducing heated tar from the stream into, an expansion zone to vaporize a substantial portion of the oil {content of the, tar} flowing the'v'apors from "said expansion zone through a cooling zone; removing tar fog from the'vapors by condensing a portion of the vapors i v during flow throughthe cooling zone, returning the condensatetogether with tar fog removedfrom the vapors to the expansion zone incontact "with vapors leaving said zone, revaporizing the lower boiling portion of th condensate thus a returned to the expansion zone and causing the vapors thus formed tov flow with the first men'- tioned vapors through-the aforesaid cooling zone,

- to the said vapor box, revaporizing the lower p i boiling portion of the condensate thus returned to V 7 rate of flow and the rate of cooling of the vapors in the condensing zone so that the'time during which each particle of the heavy creosote oil vapors is subjectedto temperatures above about tinuously withdrawing the heavy creosote oil thus 7 condensed from contact withthe vapors substane tially immediately upon formation; a V

9. A process of distilling coal tar, to produce a heavy creosote oil having a low coke residue which passing the vapors through a second cooling zone to condense heavycreosote oil vapors, regulating I i the rate of flow and the rate of "cooling time i I vapors in the firstand second cooling zones so L that the time during whichea'ch particle of the heavy creosote oil vapors is subjected to a temperature abov about 570 F. does not exceed two minutesand continuously withdrawing the condensed creosote oil from contact with the vapors.

in the second cooling zone substantially im mediately upon formation.

f 11. A process of distilling coal tar to produce a heavyvcreosote' oil having a low coke residuewhich comprises flowing coal tar in a confined stream," heating the. stream of tar to a temperature be tween about 780 andabout 8GO F., without sub i stan-tial vaporization of the tar, introducing ;heated 'tar from the stream into an' expansion zone to vaporize a, portion of the oil content of* the tar, 'fiowing the vapors from said expansion zone intoa cooling zone, removing tar fog from the vapors by'cooling the vapors inv said cooling 5 Fgtocondense a; portion of the vapors, returning I the condensate together with ftar fog removed I comprises flowing coal tar through a coil still to;

heat the tarfto a temperature of between about 780 and about 800 F., introducing the heated tar into a vapor box to vaporize a portion of the oil content of 'the tar, flowing the vapors thus produced through a cooling zone to condense a portion of the vapors, passing the condensate thus formed. to said Vapor box in contact with the vapors leaving said box, thereby returning to the vapor box the condensate formed in the sa1d cooling zone and the tar fog removed from the said zone to a temperature of about 730 to about 760 ,from th vapors to the expansion zone in. contact with vapors leaving said zone, revaporizing the lower boiling portion of the condens'atethus returned to the expansion zone and causing the vapors thus formed to fiow with the'first men-I I, tioned'vapors through the aforesaid coolingzone, passing the vapors to a second cooling zonejflow 7 ing the vapors in the second 'cooling zone through a seriesof cooling andcondensing paths, regulat- T .ing-the rate of flow and therate of cooling of the vapors in thefirstand second 'cooling zones so."

that each particle of the oil vapors is reduced to a temperature below about 57055, in less than ten '1 seconds to condense heavy creosote oil vapors, and"; continuously withdrawing condensate separately from each path of the second cooling zone to remove the condensed heavy creosote oil from contact with the vaporssubstantially immediately upon formation. i

' JOSEPH ZAVERTNIK 

